Abstract: Effects of the soil rheology on the longterm performance of engineering project is an important factor that cannot be ignored. And the stress relaxation, as a typical rheology phenomenon, has already attracted the attention of many researches. In the paper, studies on stress relaxation tests, influence factors of the stress relaxation and the constitutive models are evaluated and discussed. The available literatures suggest that the current theories on the stress relaxation of the soils are not fully developed. Specifically, the constitutive models are difficult to be applied due to the too many variables to be determined. Whereas, the empirical formulas are lack of theoretical basis. As a result, the direction of the research should be as follows: optimization analysis of the stress relaxation and the stress relaxation of lateral stress on the different retaining structures.

Key words: Stress Relaxation, Relaxation Model, Lateral Stress